In Thomas L. Friedman's 1999 book The Lexus and the Olive Tree the following observation was presented: "No two countries that both had McDonald's had fought a war against each other since each got its McDonald's". While that statement was somewhat tongue-in-cheek, his point was that due to globalization, countries that have made strong economic ties with one another have too much to lose to ever go to war with one another. While the observation may have been true, the conclusions to be drawn are unclear. The global expansion of McDonald's restaurants is a relatively recent phenomenon when put into the context of the history of warfare, and, with a few notable exceptions, has proceeded into relatively stable markets.
The 2008 South Ossetia war between Russia and Georgia is a counterexample to the theory, both countries having McDonalds at the time (started in 1990 and 1999, respectively). Other conflicts that provide possible counterexamples, depending on what one considers "a war", include the 1989 United States invasion of Panama, the bombing of Serbia, and the Kargil War along with ongoing skirmishes between factions of India and Pakistan over the Kashmir region.
The appearance of McDonald's does not end an existing state of war: the states of Lebanon and Israel have been under a state of war since 1973, with South Lebanon occupied until May 2000 and a significant flareup in 2006, which did not hinder the establishment of McDonald's franchises in Israel and Lebanon in 1993 and 1998, respectively. The two countries engaged in a brief state of warfare in the summer of 2006.