The INF treaty concerned ground based intermediate range missiles.
This is to say, missiles that are launched from ground, and whose maximum range is between 500km and 5500km. (310 - 3,420 mi)
Did the USA violate the Intermediate-Range Nuclear Forces treaty?
I just want to expand the previous answer: USA has used the Mark 41 vertical launch system on land in Poland in "Aegis ashore". This is a missile defense system, not an offensive system. The same Mark 41 VLS is a ubiquitous thing that can be found on the decks of most NATO combat vessels. Often loaded with cruise missiles. A success story in modular design.
Russia claims this means that the same canisters on land could just be loaded with cruise missiles. US claims there are modifications that prevent this. I'm not convinced by this explanation, and nobody can be without detailed engineering inspection. No honest actor would expect a potential adversary to believe such a claim.
Furthermore, after exiting INF it took only a few months for US to test a new missile that would have broken INF treaty. This is suspiciously fast. The reason is that the test was basically a naval launch tube containing a Tomahawk bolted onto a trailer. The canister is of the same Mark 41 VLS type. It is beyond obvious that US had no intention to stay in INF, the optics are so disrespectful.
The reasons can be speculated. It is true that the treaty was pretty inconsequential for US who can launch these missiles from a multitude of vessels, and aircraft. Russia has quite limited capability to do so, and was hurt more by INF.
The reason US is backing down from several treaties with Russia is probably that they feel like the appropriate great power to deal with is China, and for historical reasons most of the treaties do not concern them.