What should the USA do if a nation attacked a USS warship in international waters and killed 34 sailors?

Investigate the incident, then re-act rationally based on the evidence of what happened.

I think they should have done JUST what they DID

Both the Israeli and U.S. governments conducted inquiries into the incident, and issued reports, which concluded that the attack was a mistake, due to Israeli confusion about the identity of the USS Liberty. Some U.S. diplomats, veterans and intelligence officials involved in the incident continue to dispute these official findings, saying the Israeli attack on the USS Liberty was not a mistake, and it remains the only major maritime incident in U.S. history not investigated by the U.S. Congress.

In May 1968, the Israeli government paid US$3,323,500 as full payment to the families of the 34 men killed in the attack. In March 1969, Israel paid a further $3,566,457 in compensation to the men who had been wounded. On 18 December 1980, it agreed to pay $6 million as settlement for the U.S. claim of $7,644,146 for material damage to the Liberty itself.

On December 17, 1987, the issue was officially closed by the two governments through an exchange of diplomatic notes.

NEXT (straw man)

It would be good if they had an inquiry to find out the cause. Unfortunately the US has attacked two Australian ships and killed a number of sailors and wounded many others. No action was taken against the pilots who attacked the Australians although the ships were attached to a US Fleet sailing off Vietnam. There was never an apology or compensation.

North Korea did in 1968. The U.S.S. Pueblo and held our Navy men captive for 335 days during which a crew member died. LBJ and Clark fussed and blustered but the Pueblo is still dockside in North Korea and Kim Ill loves to show it off and North Korea's defeat over the U.S.

http://www.usspueblo.org/Pueblo_Incident/January_2...

It wasn't a warship, the liberty was misidentified as an Egyptian ship. When the North Koreans torpedoed a South Korean ship a few weeks ago where were you people?

Declare war and smash their country flat. If you don't retaliate against violence then you are just asking to be attacked again.

However your question was VERY misleading, both neither country knew what happened and it was declared a freindly fire incident. Asking without details is like asking what canada should of done about when we bombed their troops in Iraq by saying.

What should canada do if another country killed 14 of their troops in a bombing run?

Without all the details no response is possible.

We got more from Israel after the attack USS Liberty then we got from North Korea after they attacked her sister ship, USS Pueblo.

Obama would likely apologize to them for being in international waters.

There would be a US Navy Board of Inquiry, all the facts would be examined, and our ally would be exonerated because the attack was a case of mistaken identity.

Investigate first then bring the mastermind ones to justice; and do not fabricate scape goats for no political gain.