The United States believes Ukraine is making progress in its counteroffensive against Russian forces and still has "significant" reserves it has yet to commit, said U.S. General Mark Milley, chairman of the Joint Chief of Staff.
"Despite the enormous costs, Ukrainians are advancing steadily and deliberately, braving brutal and bloody battles to reclaim their homeland," Milley told reporters on July 18 after a virtual meeting of the Ukraine Defense Contact Group.
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Asked if the counteroffensive had stalled, Milley said Russian land mines are slowing the counteroffensive as Kyiv's forces face heavily fortified positions that include minefields, tank obstacles, barbed wire, and trenches.
"Right now, they are preserving their combat power, and they are slowly and deliberately and steadily working their way through all these minefields, and it's a tough fight."
It is "way too early" to judge the offensive a failure, he said, adding that the war "is going to be long, it's going be hard, it's going be bloody."
He noted that three brigades currently are being trained and equipped in Germany and other training is ongoing around the region.
U.S. Defense Secretary Lloyd Austin said the counteroffensive is a "key moment of this tragic war" as he opened the 14th meeting of the contact group, which was formed to coordinate military assistance from Ukraine's allies.
Austin reiterated that the United States will support Ukraine as long as necessary.
"We supply Ukraine with such critical equipment as air defense and ammunition. And we are not going to give up. We will continue to provide Ukraine with what it needs, when it needs it," he said.
IN PHOTOS: Residents in the eastern Ukrainian town of Lyman, a key railway hub, are awaiting their fate as Russian troops are once again threatening to recapture their shattered community. Located 50 kilometers north of Bakhmut, the town was cleared of Russian forces in October 2022.
Conquering Their Worst Fears: A Ukrainian Town Awaits Its Fate As Russian Forces Close In
The United States has spearheaded the push for international support for Ukraine, joining European allies in forming the contact group backing Kyiv.
Indiscriminate shelling by Russian troops troops earlier on July 18 killed at least four civilians in eastern and southern Ukraine, regional officials reported on July 18, as the Ukrainian military said the situation is difficult but under control in some parts of the eastern front, while in the south, incremental advances are being made.
Russia also kept up the pressure on Ukraine's air defenses, launching a fresh wave of drone strikes early on July 18 that was largely repelled, but drone debris damaged infrastructure in the Black Sea port of Odesa.
In the northern part of the Donetsk region, three civilians -- a 52-year-old woman and two men, aged 49 and 52 -- were killed by Russian shelling, regional Governor Pavlo Kyrylenko reported.
SEE ALSO: Interview: NATO's Open-Door Rhetoric On Ukraine Is Running Up Against Harsh RealitiesUkraine's Deputy Defense Minister Hanna Malyar said fighting continues in the Kupyansk area of the eastern Kharkiv region.
"The enemy offensive in the Kupyansk direction is currently unsuccessful. The fighting continues, but the initiative is already on our side," she said on Telegram.
Fighting continued on the northern flank as Russian forces try to regain lost positions, she said, noting that Ukrainian fighters "have to deal with dense mines and intense enemy fire."
General Oleksandr Syrskiy, commander of Ukrainian ground forces, said on the Telegram messaging app on July 18 that the situation was "complicated" in the Kupyansk area of the eastern Kharkiv region but that Ukrainian forces continued to register successes in parts of the south, where it pressed on with its counteroffensive.
"The situation is complicated, but under control. The enemy is transferring reserves to the Bakhmut area [of Donetsk], trying to stop our advance," Syrskiy said. "At the same time, the enemy concentrates its main forces in the Kupyansk direction, where Ukrainian soldiers are on the defense."
WATCH: A section of the Crimea Bridge was damaged by a deadly explosion on July 17. Moscow said two people were killed and a child was injured in the blast that it blamed on Ukrainian maritime drones.
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Moscow Blames Kyiv For Deadly Crimea Bridge Blast
Early on July 18, Serhiy Bratchuk, a spokesman for the military administration of the Odesa region, said Ukraine's air defenses had repelled a Russian air attack on the port city.
Ukraine's Operational Command South later said in a statement that "debris from the destroyed missiles and the blast wave from the downing damaged the port infrastructure facilities."
The strike on Odesa, which is crucial for Ukraine's grain exports, came a day after Moscow pulled out of a UN-brokered deal to allow the transit of the grain, refusing to extend it after it expired on July 17.
Russia overnight also launched an attack on Mykolayiv region, using Iranian-made drones that caused a fire, regional Governor Vitaliy Kim, said on Telegram.
Russia's Defense Ministry and the Moscow-installed head of annexed Crimea, Sergei Aksyonov, said on July 18 that Russian forces repelled an attack by 28 Ukrainian drones on the eastern part of region.
The ministry said in a statement that 17 drones were destroyed and 11 were disabled by electronic means. Both the ministry and Aksyonov said the attack caused no casualties or damages.
The report, which could not be independently verified, came a day after an attack by seaborne drones on the bridge that links Crimea with Russia that killed two people and caused major damage and a disruption to traffic. Russia has blamed Ukraine for the attack.
Kyiv did not claim responsibility, but Ukrainian media quoted sources as saying security services had deployed maritime drones.
In a statement quoted by the TASS news agency, Russia's Defense Ministry said on July 18 that it had carried out "revenge" strikes in Odesa and Mykolayiv against sites that Moscow claimed were used by Ukraine to prepare seaborne drones of the type suspected to have hit the Crimea bridge.