71 killed in Israeli attack on Iran prison, official says

No Americans were hurt and "hardly any damage was done" by Iran’s "very weak" and "expected" missile attack on the United States’ Al Udeid Air Base in Qatar on Monday, President Donald Trump wrote on Truth Social, adding that the attack was "very effectively countered."

Trump also said no Qataris were killed or hurt.

Trump said Iran fired 14 missiles. He said "13 were knocked down, and 1 was ‘set free,’ because it was headed in a nonthreatening direction." A U.S. official confirmed that 13 of the 14 Iranian missiles were intercepted by the U.S. and Qatar, and the 14th did not end up in Qatar. The official also confirmed that little damage was done.

Trump said Iran has "gotten it all out of their ‘system,’ and there will, hopefully, be no further HATE."

"I want to thank Iran for giving us early notice, which made it possible for no lives to be lost, and nobody to be injured," Trump continued. "Perhaps Iran can now proceed to Peace and Harmony in the Region, and I will enthusiastically encourage Israel to do the same."

In a separate post, Trump wrote, "CONGRATULATIONS WORLD, IT’S TIME FOR PEACE!"

After attacking a U.S. base in Qatar on Monday, Ayatollah Ali Khamenei, the supreme leader of Iran, posted on social media saying they will not surrender.

The post was accompanied with a picture of a burning American flag.

"We have not violated anyone’s rights, nor will we ever accept anyone’s violation; this is the logic of the Iranian nation," Khamenei said.

-ABC News' Will Gretsky

The State Department has issued a new worldwide caution alert prompted by the conflict between Israel and Iran.

"The conflict between Israel and Iran has resulted in disruptions to travel and periodic closure of airspace across the Middle East. There is the potential for demonstrations against U.S. citizens and interests abroad. The Department of State advises U.S. citizens worldwide to exercise increased caution," the alert reads.

Earlier this month, the State Department issued a regional alert related to the conflict, advising Americans in North Africa and the Middle East to exercise increased caution.

-ABC News' Shannon Kingston

The Justice Department currently has "countless" open investigations into threats to the U.S. homeland, Attorney General Pam Bondi said Monday in testimony to lawmakers on the House Appropriations Committee.

When asked about the presence of potential Iranian "sleeper cells" being activated in the U.S. in the wake of the military's strikes on Iran's nuclear program, Bondi said she couldn't answer such a question in an unclassified setting.

"I can't talk about that in this setting but what I can tell you is I know Homeland Security, I know the FBI -- they are focusing on doing everything we can to keep our nation safe, and they will continue to do that," Bondi answered. "Yeah, it's a frightening time in which we live right now, but President Trump is committed to keeping all Americans safe, and we look forward to working with you on that."

Bondi further confirmed that the department believes "well over 1,000" Iranian nationals entered the country illegally over the "last several years" and the department is on "high alert" regarding any potential illegal activity by those in the U.S.

-ABC News’ Alexander Mallin