The NHL has never shut down because of war. But war has played a significant role in hockey history, and it could have an impact on professional and international championships to be decided in the next few weeks. A lengthy war in Iraq could force schedule changes or cancellations.

The NHL says it will continue with business as usual. Media reports suggest the league has a contingency plan to postpone games for a few days if the U.S. imposes restrictions on travel or border crossings. But the possibility of a long-term shutdown is not being considered. An American Hockey League executive says minor pro leagues will likely follow the NHL's lead.

International hockey will also continue. But with several high profile international events scheduled for next month, that situation could change quickly.

So far, no teams have pulled out of the women's world hockey championship in Beijing, which begins April 3. "You think about it," Canadian team captain Cassie Campbell told Canadian Press. "A lot of us have had conversations wondering if the world championships will be cancelled if there is a war."

There is also the possibility of the tournament going ahead without an American team. That would be a serious blow to the women's championship, which thrives on a fierce Canada-U.S. rivalry. "The best hockey we have right now is to play against the United States," said Campbell. "To not have that opportunity in China, it wouldn't seem like a real world championship without them there."

The world under-18 men's hockey championship in Russia and the men's world hockey championship in Finland are also scheduled for April. There have been no withdrawals from either tournament, but the International Ice Hockey Federation says it is monitoring the situation.

European professional leagues, Canadian junior leagues and the NCAA have made no schedule changes.

International hockey has often played out against a backdrop of tension and conflict. From the 1960s through the 1980s, games between North American and Soviet Bloc teams reflected Cold War tensions. But perhaps the most memorable "political" games in hockey history took place at the 1969 world championship, a few months after a Soviet invasion crushed the democracy movement in Czechoslovakia. The Czechs defeated the Soviets twice during the tournament (which was played in Sweden), causing thousands to pour into the streets of Prague in celebration. A sign in the crowd told the Soviets, "This time you can't count on your tanks."

The NHL has continued play through all conflicts. But World War II had a profound effect on the league. Many players interrupted their careers for military service (although team owners often intervened to ensure that stars received non-combat assignments). The depletion of NHL rosters created opportunities for athletes who might otherwise have never played an NHL game .

In response to the dilution of talent during World War II, the league changed its rules to encourage a faster paced game. Until 1943, a player was not allowed to make a forward pass across his own blueline. That changed in the 1943-44 season, when the NHL ruled that players could pass from their defensive zone up to the middle of the rink, which would be marked by a new red line at centre ice. The red line remains in place to this day.

The war also shifted the power balance in the league. While other NHL teams watched their players depart for military camps, the Montreal Canadiens took advantage of the war years to get a head start on a new dynasty. By finding jobs for players in essential industries like munitions and shipbuilding, the Montreal Canadiens kept their talent home, building the foundation for several Stanley Cup championships.