Sen. James Lankford, R-Okla., did not rule out supporting putting U.S. troops on the ground in Iran, saying in an interview on NBC News’ “Meet the Press” that “we’ve got to be able to know what the objectives are and what they’re actually carrying out.”

Asked by moderator Kristen Welker whether he would support President Donald Trump deploying troops into Iran, Lankford emphasized the importance of being able to end a conflict after it begins.

“To be very clear on this, the worst thing that can happen is to be able to have this kind of conflict start and to not end it, to leave it undone. We’ve got to be able to finish this,” he said, going on to point to Iran’s history of supporting attacks against Americans.

Asked later to confirm that he was not ruling out supporting U.S. troops in Iran, Lankford said it “depends on what boots we’re putting on the ground.”

“If this is special forces to be able to carry out a specific operation — get in, get out — that’s very different than long standing occupation,” he said.

Thousands of additional U.S. troops are arriving in the region, according to a social media post from U.S. Central Command. NBC News reported last week that Trump approved the deployment of more than 1,000 soldiers from the 82nd Airborne Division to the Middle East.

NBC News has previously reported that Trump is weighing options for putting U.S. troops on the ground, including options aimed at securing the Strait of Hormuz, retrieving Iran’s highly enriched uranium, or seizing Iranian oil facilities to deprive the government of finances and extract concessions.

Earlier this month, Trump said he was “not putting troops anywhere,” but added that if he were, he would not tell reporters.

Asked Sunday whether Trump needed congressional approval to deploy U.S. troops into Iran, Lankford hedged, saying it was “contingent” on how the troops were used.

“If we had a long standing war that’s happening, go back again to what happened in Iraq or in Afghanistan, yes,” Lankford said. “If this is to protect Americans and to be able to make sure that we’re in there for a season and we’re stopping and getting out, that’s very, very different. So again, this is all contingent.”

Senate Republicans have previously rejected multiple war powers resolutions aimed at limiting Trump’s ability to launch further military action against Iran without congressional approval.

Meanwhile, Iran’s parliament speaker said Sunday that the country is ready to counter a U.S. ground attack, “waiting for American soldiers to enter on the ground so they can set them ablaze and punish their regional partners forever.”